Granulator mill

ABSTRACT

A granulator mill includes a mill housing with an openable part and a fixed part, a rotor which is rotary inside the mill housing and has a number of blades for co-operation with at least one fixed blade mounted in the mill housing and a discharge section whose interior is discrete from the interior of the mill housing by means of a grid through which granulate passes from the mill housing to the discharge section. The openable part of the mill housing is connected to the fixed part by the intermediary of a pivot device with a pivot axis which is substantially vertical in the normal position of use of the granulator mill.

TECHNICAL FIELD

The present invention relates to a granulator mill which comprises amill housing with an openable section and a fixed section, a rotor whichis rotary inside the mill housing and has a number of blades forco-operation with at least one fixed blade mounted in the mill housing,and a discharge section whose interior is discrete from the interior ofthe mill housing by means of a grid through which granulate passes fromthe mill housing to the discharge section.

BACKGROUND ART

In the employment of granulator mills within the plastics industry forrecycling or reuse of plastics, it is necessary to carefully clean theinterior of the granulator mill before a change can be made to a newplastics quality or plastics colour. This entails demands, on the onehand, that the interior of the mill housing must be accessible, as wellas the interior of the receptacle section in which the finishedgranulate is collected and from which the granulate is conveyed off, asa rule via a conduit. For this reason, mill housings have previouslybeen constructed to be openable so that a part is openable in relationto that part in which the rotor of the granulator mill is journalled. Inthese prior art constructions, the openable part is pivotal about ahorizontal axis and suspended in its lower edge.

Constructions of this type entail demands for auxiliary tools on openingand closing the openable part, since this is so heavy that it cannot behandled manually.

The openable part further has a very limited opening angle because ofthe suspension in an area beneath the mill. The reason for this is thatthe substrate on which the granulator mill stands quite simply preventsopening of the openable part to any larger opening angle.

Further, it has often been necessary in these prior art constructionsfirst to dismantle the discharge section in order to be able to get atthe openable part at all.

Taken as a whole, prior art mills have been difficult to accessinteriorly so that, as a result, cleaning of a mill has proved to becircumstantial and time-consuming.

Problem Structure

The present invention has for its object to design the granulator millintimated by way of introduction so that the drawbacks inherent in priorart technology are obviated. In particular, the present invention hasfor its object to realise a granulator mill in which the openable partmay readily be opened and closed manually without auxiliary tools oraids, where considerably greater access is afforded to the interior ofthe mill in the open state than has been possible hitherto, and alsowhere the discharge section and grid are readily accessible forcleaning.

Solution

The object forming the basis of the present invention will be attainedif the granulator mill intimated by way of introduction is characterisedin that the openable part of the mill housing is connected to the fixedpart by the intermediary of a pivot device with a substantially verticalpivot axis in the normal position of use of the granulator mill.

As a result of these features, the advantage will be afforded that theopenable part may readily be opened manually, since its point of gravitydoes not undergo any change in height on opening and closing. Further,the pivoting about the vertical axis permits the opening angle to bemade considerably greater, for which reason accessibility iscorrespondingly improved.

According to expedient and advantageous embodiments of the presentinvention, the discharge section and the grid are suitably fixed in andsupported by the openable part of the mill housing and are pivotaltogether therewith.

As a result of these features, it is possible, in a simple andconvenient manner to gain access also to these components for cleaning.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will now be described in greater detailhereinbelow, with particular reference to the accompanying Drawings. Inthe accompanying Drawings:

FIG. 1 is a perspective view of a granulator mill seen obliquely fromabove from a first end of the rotor shaft;

FIG. 2 is a view corresponding to that of FIG. 1, the granulator millbeing, however, seen from the opposite end of the rotor shaft;

FIG. 3 is a view corresponding to that of FIG. 1, the openable part ofthe mill housing as well as the infeed hopper of the granulator millbeing open;

FIG. 4 is a vertical cross section through the granulator mill;

FIG. 5 is, on a larger scale, a perspective view of the region accordingto the arrow 1 in FIG. 1; and

FIG. 6 shows, in perspective, the openable part of the mill housing seenfrom the inside.

DESCRIPTION OF PREFERRED EMBODIMENT

In FIGS. 1 and 2, which show a granulator mill in perspective seen fromdifferent directions, reference numeral 1 relates to a fixed part of amill housing in which the rotor of the granulator mill is journalled.Correspondingly, reference numeral 2 relates to an openable part of themill housing, while reference numeral 3 relates to the removable rearside of the mill housing and reference numeral 4 relates to the infeedhopper of the granulator mill. The infeed hopper 4 is openable inrelation to the mill housing by pivoting about the pivot axis shown bythe broken line 5. Since the infeed hopper is of considerable weight andsize, auxiliary equipment is required for opening and closing, in theform of a motor 6, a toothed gear 7 and a screw device 8 connectedthereto.

In order to avoid the use of mechanical aids on opening and closing theopenable part 2 of the mill housing, this is arranged in such a mannerthat it substantially does not undergo any vertical displacement duringan opening and closing cycle. This is realised in that the openable part2 is secured in the fixed part 1 of the mill housing by means of a pivotdevice which is disposed, in the vertical direction, to keep the pointof gravity of the openable part 2 substantially constant and which, tothis end, is provided with a substantially vertical pivot axis 9illustrated by broken lines in FIGS. 1 to 3 and 6.

The pivot device with the substantially vertical pivot axis 9 hasmutually pairwise engaging guide surfaces, on the one hand on the fixedpart 1 of the mill housing and, on the other hand on its openable part2. These guide surfaces are at right angles to the pivot axis 9 and aredisposed, on the one hand on projecting lugs 10 on the fixed part 1 ofthe mill housing and, on the other hand on projecting lugs 11 on theopenable part 2 of the mill housing. In the illustrated embodiment (FIG.2), it is apparent that the fixed part 1 of the mill housing has foursuch guide surfaces, which also applies to the openable part 2.

The pivot axis 9 is defined by a cylindrical pin which constitutes thephysical pivot shaft between the fixed part 1 and the openable part 2.This implies that the pivot shaft (not shown on the Drawings) guides theopenable part 2 in a direction towards and away from the rotor of thegranulator mill of which only one stub shaft 12 is shown in FIG. 2.

It will be apparent from FIGS. 3 and 4 taken together that the rotor isprovided with a number of blades 13 at its periphery, in the illustratedembodiment three in number. Correspondingly, there are fixed blades 14in the mill housing, both in the fixed part 1 and in the openable part2, of which blades the openable part has at least one. The fixed blades14 are disposed closely adjacent to and co-operate with the blades 13 onthe rotor and are, therefore, distributed around the peripheral surfaceof the rotor.

Internally in the rotor, but also internally in the mill housing, thereis a space in which the comminution proper of the plastic material intogranulate takes place. Where this comminution has proceededsufficiently, the finely-divided particles or granulate pass through agrid 15 which may have varying mesh size. This grid 15 surrounds therotor along a part of its periphery. On the underside or outside of thegrid, there is a receptacle section 16 in which the granulate iscollected and from which the granulate is conveyed off via an outlet 17.The receptacle section 16 has, in the axial direction of the rotor,approximately the same extent as the blades 13 and 14.

According to the present invention, both the grid and the receptaclesection 16 are secured in and carried by the openable part 2 of the millhousing and they are, therefore, pivotal together with it. However, itis also conceivable that the receptacle 16 may be arranged on the fixedpart 1 of the mill housing.

The grid 15 extends about the periphery of the rotor and in under it andat least up to a vertical line through the centre of the rotor shaft,but preferably also a short distance past this vertical line. In ordernot to impede the opening capability of the openable part 2, the part 18of the grid 15 located under the rotor is disposed in a tangential planeto the circumference of the rotor, this tangential plane being at rightangles to the pivot axis 9. This part 18 of the grid 15 may, therefore,suitably be substantially planar.

As is apparent from FIGS. 3 and 4, the openable part 2 of the millhousing surrounds approximately 140°-180°, preferably approximately 160°of the circumference of the rotor.

In FIG. 4, reference numeral 19 relates to a number of plates which aredisposed with spacing in the longitudinal direction of the rotor shaftand which have edges facing towards the rotor which support the grid 15.These plates 19 lie in the diameter plane to the rotor at right anglesto its centre axis. Since the grid 15 enjoys good support from thearcuate edge surfaces of the plates 19 facing towards the rotor, thegrid 15 is quite simply placed in a recess 31 in the openable part (FIG.6). As was intimated above, the grid is guided in the radial directionby the above-mentioned plates 19, while, in the axial direction and inthe circumferential direction, it is guided and positionally fixed bythe edges of the recess 31 in the openable part 2.

It will also be apparent from the Figures that the receptacle section 16is placed beneath the openable part 2 of the mill housing. Suitably, thereceptacle section 16 may be guided in a pair of sliding rails orgrooves 32 on the underside of the openable part 2 so that thereceptacle section 16 may thereby readily be drawn out from or slid intoposition again beneath the openable part 2.

In the open state of the openable part 2, approximately ¾ of theperiphery of the rotor is free and readily accessible for cleaning.Further, after lifting off the grid 15, it is simple to gain access tothe inside of the openable part 2 in the plates 19 but also the interiorof the receptacle section 16.

In FIG. 3, the openable part 2 is shown in only the partly open state.If the space around the granulator mill permits, the openable part maybe opened to up to circa 180° about its pivot axis 9, which impliesextraordinarily good access to the interior parts of the mill. Forpositioning the openable part in the correct position when this islocated in the closed position, both it and the fixed part 1 of the millhousing have mutually engaging guide members.

FIGS. 3 and 5 show the one journal box 20 for the shaft of the rotor.The journal box 20 has a projecting flange 21 (FIG. 3) by means of whichthe journal box 20 is secured in the fixed part 1 of the mill housingwith the aid of a number of bolts 22 (FIG. 5). The peripheral edge ofthe flange 21 serves the purpose of guide surface which is accommodatedin a corresponding seat or recess 33 on the openable part 2 of the millhousing. As a result, the openable part of the mill housing willaccurately be positioned in relation to the rotor.

In order to realise reliable engagement between the guide surface andthe seat use is made of bolts 23 which, with their one end, are securedin the fixed part 1 of the mill housing and which, with their other end,extend through a projecting edge portion 24 of the openable part 2. Thebolts 23 may be secured in the fixed part 1 of the mill housing and may,therefore, also be designated pin bolts which extend through apertures25 in the projecting edge portion 24. On the outside of this edgeportion, use is made of a locking rail 26 which has keyway-shapedapertures 27. After release of the nuts 28 on the bolts 23, the lockingrail 26 may be moved downwards so that it can be removed from the nutsin that these pass through the greater part of the apertures 27.

Reference numeral 29 (FIG. 5) relates to a safety switch which issecured in the infeed hopper 4 and which fixedly locks a key 30 which issecured on the locking rail 26 when the granulator mill is in operationand at least during as a long a time as is required for the rotor tohave time reliably to have parked once the drive motor of the rotor hasbeen turned off. Only when this has taken place can the locking rail 26and the key secured therein thus be removed and thereby the openablepart 2 of the mill housing be opened. In a corresponding manner, therotor cannot be restarted until the infeed hopper 4 is closed so thatthe safety switch 29 is located in the correct position for insertingthe key 30 when the locking rail 26 has been put in place.

The present invention may be further modified without departing from thescope of the appended claims.

1. A granulator mill comprising: a mill housing with one openable partand a fixed part; a rotor which is rotary inside the mill housing andhas a number of blades for co-operation with at least one fixed blademounted in the mill housing; and a discharge section whose interior isdiscrete from the interior of the mill housing by means of a gridthrough which granulate passes from the mill housing to the dischargesection, wherein the openable part of the mill housing is connected tothe fixed part by the intermediary of a pivot device with a pivot axiswhich is substantially vertical in the normal position of use of thegranulator mill, wherein the grid is provided on the openable part ofthe mill housing, wherein at least one fixed blade is provided on theopenable part, wherein the discharge section is secured in and carriedby the openable part of the mill housing and is pivotal togethertherewith, and wherein the grid has a curved portion to encircle atleast a portion of the periphery of the rotor and a substantial flatportion beneath the rotor and the grid is received in a recess in theopenable part of the mill housing.
 2. The granulator mill as claimed inclaim 1, wherein the grid is supported, on the side remote from therotor, by a number of plates provided on the openable part of the millhousing and extending perpendicular to an axis of rotation of the rotor.